Fatigue is a quantitative or qualitative decrease in the capacity for work and the efficiency of accomplishment that result from a bodily or mental activity, also accompanied by perceived feelings of fatigue including those of lassitude, discomfort and weakness. The reduced functions and the feelings of fatigue may occasionally occur simultaneously but they also occur with time lags or even independently. Such physiological fatigue is usually relieved by rest to restore the initial normal state and it will not last for long. According to “A Survey on Public Perception of Health” conducted by the Prime Minister's Office in 1985, over 60% of the people surveyed complained of fatigue but 70% of those who complained of fatigue said that “their fatigue is relieved by a night's sleep.” However, this pattern is changing in recent years. According to the epidemiological research conducted by the fatigue survey study group of the Health and Welfare Ministry in 1999, the proportion of the people who perceived fatigue remained unchanged and accounted for about 60% but then as much as 60% of those people were reported to have felt tired for more than six months. Thus, in the 14 years from 1985 to 1999, more people became afflicted with chronic fatigue, indicating a change in the nature of fatigue (Nonpatent Literature 1). More recently, a disorder called “chronic fatigue syndrome (CFS)” and death by overwork are presenting themselves as big social problems. However, the causes of fatigue and its mechanism are of great variety and in spite of the work being conducted by many researchers, the entire picture of fatigue is yet to be seen and there have been established no definitive methods of treating or preventing fatigue-caused diseases including chronic fatigue syndrome and death by overwork.
Most recently, so-called “anti-fatigue substances” that have a fatigue-relieving action or an action for promoting the restoration of the normal state from fatigue have been reported. For example, certain kinds of amino acid compositions (Patent Literature 1), L-carnitine and histidine-related dipeptides (Patent Literature 2), hawthorn extracts (Patent Literature 3) and the like have been reported to have a body strength increasing action. In addition, nutrition support compositions containing ascorbic acid have been shown to be useful for the purpose of furnishing nutrition when one has lost their body strength due, for example, to exercise or at such times that one is tired (Patent Literature 4).
As regards sesamin-class compounds (hereinafter used as the collective term for sesamin and its analogs; sesamin analogs may be exemplified by espisesamin, as well as sesamin, sesaminol, episesaminol, sesamolin, and the like), experiments with purified sesamin-class compounds have led to the reporting of various actions including the action of inhibiting the metabolism of cholesterol and bile acid in the intestines (Patent Literature 5), the action of alleviating the symptoms of withdrawal from alcohol or tobacco intoxication (Patent Literature 6), the action of improving hepatic functions (Patent Literature 7), the action of in vivo stabilization of highly unsaturated fatty acids (Patent Literature 8), the action of inhibiting Δ5-desaturase (Patent Literature 9), the action of suppressing migraine (Patent Literature 10), the action of inducing apoptosis in human leukemic cells (Patent Literature 11), the action of suppressing the oxidative decomposition of melatonin (Patent Literature 12), and an autonomic nerve regulating action (Patent Literature 13).
Patent Literature 1: JP H09-124473 A
Patent Literature 2: JP 2001-046021 A
Patent Literature 3: JP H08-47381 A
Patent Literature 4: JP H06-327435 A
Patent Literature 5: JP Patent No. 3183664
Patent Literature 6: U.S. Pat. No. 4,427,694
Patent Literature 7: JP Patent No. 3075358
Patent Literature 8: JP H11-269456 A
Patent Literature 9: JP Patent No. 3070611
Patent Literature 10: JP 2003-183172 A
Patent Literature 11: JP 2001-151676 A
Patent Literature 12: JP 2000-143546 A
Patent Literature 13: WO 2004-105749
Nonpatent Literature 1: Hiroh no kagaku (Science of Fatigue) (9. Hiroh kaifuku jyohoh (Information on Recovery from Fatigue); 2001, Kodansha